Thermal ignition of black powder

It will be appreciated from the previous paragraphs that the ignition of explosives such as black powder is not an instantaneous process. Classically, as the temperature of the black powder is raised, slow decomposition sets in according to the process  

Black powder — gaseous products -I- solid products -I- heat 

Gas evolution from gunpowder measured at atmospheric pressure and 290 °C. 

Since E is the numerator of a negative exponent, the reaction rate increases as E decreases. 

The time to ignition can be expressed by equation (2.10) which is similar in form to the Arrhenius equation. 

Activation energies for black powders (and many other energetic materials) can be determined empirically from the logarithmic form of the Arrhenius equation (2.11)  

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